Prenatal testing involves testing a fetus for the presence of various hereditary or spontaneous genetic disorders, such as Down syndrome. One of the most common procedures for detecting abnormalities before birth is amniocentesis in which a sample of the fluid surrounding the fetus (amniotic fluid) is obtained. In amniocentesis, after anesthetizing an area of abdominal skin, a needle is inserted through the abdominal wall into the amniotic cavity. During the procedure, ultrasonography is performed so that the position of the fetus can be monitored and the needle guided into place without touching the fetus. Amniotic fluid is collected through the needle into a syringe, and the needle is then removed. Another fetal examination includes chorionic villus sampling (CVS). Both amniocentesis and CVS are invasive, and as such carry a small but definite risk to the mother and fetus. After amniocentesis, the chance of miscarriage due to the procedure is about 1 in 200.
Ultrasound has been used in a number of medical applications. Examples of clinical applications of ultrasound include imaging, stimulation of the healing of soft tissue, during topical application of a medication, and for enhancement of transdermal drug delivery into the circulatory system. In addition, ultrasound has also been used for selectively altering the permeability of cell membranes. This alteration is reversible and the effect can be controlled as to its extent and rate.
Further, a method for non-invasively monitoring the concentration of an analyte in an individual's body using ultrasound and for increasing permeability of a selected area of the individual's body surface have been described. The method makes use of chemical enhancers in combination with ultrasound sonication.